This is an implementation of the [JSON Schema specification](http://www.json-schema.org) written in pure Java. This allows pure server side JSON schema validation if this is what you are looking for.
The draft serving as a reference is, at the moment, draft version 3, which can be found [here](http://json-schema.org/draft-03/schema") (version 4 is around the corner, for some defintion of "corner" -- understand, days, or a few weeks). This implementation has full support for instance validation using draft v3, and can be extended to support draft v4 easily.
Version 0.2.1 is out: see [here] (https://github.com/fge/json-schema-validator/wiki/ChangeLog) for a list of features.
For a detailed discussion of the implementation, see [here](https://github.com/fge/json-schema-validator/wiki/Status). For a list of planned features for next versions, see [here](https://github.com/fge/json-schema-validator/wiki/Roadmap).
Please see the wiki for more details.